1. Technical Field
The present invention generally relates to electrostatic paint application devices, and more particularly to an apparatus and method for reducing undesirable powder accumulation on electrostatic paint devices.
2. Description of Related Art
Electrostatic powder coating is routinely used in industry to coat an object with a paint that is applied in powder form. After the object is coated with a sufficient layer of powder, it is routed to an oven for the application of heat, which converts the powder coating into a homogeneous and strong paint layer as a result of the powder particles melting together, including polymerization.
Electrostatic paint application devices are used to apply powder paint. These devices typically use a rotating cup to disperse powder into a compressed air stream which is directed toward the target, in this case, an automotive body-in-white (an unpainted unadorned metal body). The face of the rotating cup typically has a metal plate, which, when electrically charged creates a corona field. This field is attracted to the closest electrical ground which is, not coincidentally, the automotive body-in-white, which is intentionally given an electric charge.
As powder particles are propelled by air, they pass through the corona field, where they accumulate charged ions. This effectively charges the paint particles. These charged paint particles are then physically, by means of the compressed air stream, and electrically, by means of the difference in charge, propelled to the surface of the body-in-white. However, not all paint particles acquire a charge for a variety of reasons, such as thermal and aerodynamic effects. Some particles thus do not make it to the body in white surface. This is typically referred to as stray powder.
Stray powder can, if not properly controlled, accumulate on the surface of the powder applicator. This powder may accumulate in large quantities and subsequently fall on the rotary bell cap and then onto the coated surface, causing undesirable paint defects. These defects typically require a manual sanding operation in order to remove them prior to application of a top coat (color and/or clear coat). The sanding of these defects generates contaminants, which can be extremely harmful to the appearance of the top coated article, as well as requiring significant labor and expenses. The powder accumulation on surfaces other than the object to be painted also causes numerous production interruptions to allow maintenance personnel to remove the undesired powder deposits, resulting in the reduction of production rates.
Known methods for cleaning the powder applicators described above generally require shutting down the system, manually applying low pressure air, and wiping applicable surfaces with rags to remove the deposits.
In view of the foregoing, it is one objective of the present invention to provide an apparatus and method for reducing undesirable powder accumulation on a powder application device.
It is an additional objective of the present invention to provide an apparatus and method for reducing undesirable powder accumulation on a powder applicator device which is easily assembled and installed.
Additional advantages and features of the present invention will become apparent from the subsequent description and claims taken in conjunction with the accompanying drawings.